Multicolor printing on a continuous web



Feb. 21, 1961 a. N. AUERBACHER 2,

MULTICOLOR PRINTING ON A commuous WEB Filed Oct. 3, 1957 34 mg 96 5 .22/02 A90 nited States MULTICOLOR PRINTING ON A CONTINUOUS WEB George N.Auerbacher, Springfield, NJ assignor to Champlain Company, Inc.,Bloomfield, N.J., a corporation of New York Filed Oct. 3, 1957, Ser. No.688.034

Claims. (Cl. 101-481) individual units of the press line driven by saidshaft.

Thus, additional motion or velocity may be added-or subtracted at anyunit to keep it in proper registration. To do this at high web speeds,photoelectric scanners have been devised which are located betweenunits, and which automatically feed positive or negative motion at'therunning register, as may be required to maintain registration. Otherexpedients for this purpose are employed, such as movable compensatorrollers which slightly lengthen or shorten the web between one press andthe next.

In a multicolor press, the printing cylinders theoretical- 1y all havethe same diameter, and it has been assumed that in such case the unit ofprinting matter or so-called layoff would be constant, and thatdeparture from registration arises from variables such as web stretch oryield; minute changes in the web drive velocity at the printingcylinder; minute differences in cylinder diameter, etc. I have foundthat the difiiculty may arise from minute differences in the length ofprinted matter or layoff which may occur even at a single printingcylinder of unquestioned constant diameter. An object of the presentinvention is to overcome suchdiiferences, and maintain uniform layofi ofthe printed matter on a web, particularly when dealing with acomparatively thick web.

This helps maintain registration, and the object of the invention may bedefined more broadly as being to maintain registration of multicolorprinting. In theory, one might eliminate running registers, but inasmuchas the uniform layoff of my invention presupposes perfect initialregistration, and inasmuch as running registers are anyway convenient,and almost a necessity to secure initial regis tration, my invention inpreferred form is used along with running registers, and serves tominimize the work which must be done by the running registers.

Web scanners are employed to detect any departure from uniform layoff,and in accordance with a further feature and object of my invention, thesame web scanners may be employed for both purposes, that is, to helprestore uniform layoff in the event of a departure from uniform layoff,and to help restore registration in the event of a departure fromregistration.

To accomplish the foregoing general objects, and other ice Fig. 1 is aplan view of a multicolor printing press enibodying features of myinvention;

Fig. 2 is an elevation of the same;

Fig. 3 is a schematic elevation of a part of the press. shown in Fig.2,drawn to enlarged scale; and

Figs. 4 and 5 are companion fragmentary views explanatory of theunderlying principle of the invention.

Referring to the drawing, and more particularly to Fig. 3, the righthand unit of the printing press there shown is of the intaglio orrotogravure type. It comprises an engraved printing cylinder 12, and acooperating impression cylinder 14. Cylinder 12 is inked in any desiredfashion, as by use of an ink fountain 16, 'and the excess ink is scrapedfrom the cylinder by a suitable doctor blade, schematically representedat 18. The web 20 is passed between the cylinders 12 and 14, and theunderside thereof receives ink from the engraved impressions in thecylinder.

The web is then dried by passing the same through a suitable drier,indicated at 22, following which it is led to the next printing unit.

Referring now to Fig. 4 of the drawing, the printing cylinder 12 may beassumed to be conventional in that it is made of a non-yieldingmaterial, specifically metal, which is chemically etched to form theintaglio impressions therein. The impression cylinder 14 also isconventional, in at least to the extent that it is made of a yieldablematerial, typically rubber or its equivalent, as shown at 24. 'The web20 is shown approaching the cylinder 12 in a downwardly slopingdirection at 26, and leaving the cylinder 12 in an upwardly slopingdirection at 28. In other words, in Fig. 4 the web 20 is wrappedpartially around the impression cylinder 14, and it is convex inrelation to the printing cylinder 12. If the web has significantthickness, the upper surface is contracted, and the lower is stretched,relative to the mean or pitch length of the web indicated by the brokenline 30.

The printing cylinder 12 applies printed matter to the underside orstretched surface of web 20, and on reflection it will become evidentthat when the web is subsequently straightened or laid flat, the printedmatter will be slightly contracted. The layoff on the web then will beslightly less than the circumference of the printing cylinder 12.

Referring now to Fig. 5, assumes that the web is wrapped partiallyaround the printing cylinder 12, as shown in broken lines, that is, itapproaches the cylinder in upwardly sloping direction as shown at 32,and leaves the cylinder in downwardly sloping direction, as shown at.

34. Differently expressed, the web is concave in respect to the printingcylinder 12. Here again, one face of the web is stretched, and the othercontracted, relative to the pitch line, but in opposite sense from whatis shown in Fig. 4. Thus, when the web is subsequently straightened orlaid flat, the printed matter on the bottom face of the web will bestretched or lengthened slightly, and the layoff will be slightlygreater than the circumference of the printing'cylinder.

Now, in practical apparatus of types already in common use, includingthe type illustrated in Figs. 1-3, it would not be convenient to keepchanging the angle of approach and departure of the web from theprinting cylinder. However, I have found that for purposes of thepresent invention, this may be done in effect, by

' changing the pressure exerted on the web by the impression cylinder.This is so because of its yieldable nature, and referring to Fig. 5 ofthe drawing, the web 20 shown in solid lines approaches and leaves theprinting cylinder 12 in downward and upward sloping directions, 26

and 23, exactly as in the case of Fig. 4, but increased pressure betweenthe cylinders has caused a surface C0117 tact instead of a line contactwith the printing cylinder at 36, resulting from compression or yield ofthe material of -the impression cylinder at 38. The portion of sprees?the. web immediately atthe. printing cylinder is concave rather thanconvex in respect to the printing cylinder, and this is so despite theslope of the Web at 26 and 23.

Thus,=a variation in pressureexerted on theimpression cylinder isequivalent to:a:change :in TWebrdlICCtlOl'I; or in convexity versusconcavity; relativeqtou the? printing cylinder. Thisin turn causes.achange inwlayoff of the printed matter on the .web, andrthusthepressure .ofthe impression cylinder may be usedntozvary, therlength ofthe layoff in one direction orthe other;

Reverting. now to Fig. 3 .of the drawing, theapparatus includesa'pressure exerting means Atlwtoexert pressure oncthetweb between thecylinders.12 and 14ft ltsfurther comprises .a. detector means 110, .44;:46:to:1deteet any departure'ifro-m uniform layofizof'fthe.printedi-matter, and .further comprises: means;48 and: t) :for varying:the pressure'exerted' on the. webaby, .the;means.;40:in: thatdirection-which tends to restore uniformclayofil't Considen'nglhe:invention in greatercdetail, .andrreferring: more; particularly to"Figsa l and. 2,. web; so is: 1111- wound vfrom.a..large reel.54,and:.then;passed through appropriate. units such as. a splicer.56,-decurler 53 and.

pull unit 66. The roll 54 maybe-amounted :onta roll carrier 62: designedto facilitate changingv from one roll as it expiresto a new roll,shownatdS. The expired roll may thenbe removed and replaced by. anotherfull rollJpreparatory to expiration of thesecondroll, and

so one The: web feed or. pull unit .69 is'arrangedfor finespeedadjustment, as: by a means of an infinitely variable drive'64.There is usually a slack loopofi ahead of the feed unit. 66. The web.thengoes to a series of units for multipleoperations on the'web. Inthepresent case, a multicolor gravure'press is shown,.comprising printingunits 71 72,74, 76 and 78, These are. followed by a pull unit 80, whichmay-befollowed by still further units, not shown; for:scoring, creasing,punchingor/an-d cutting the web.

Referring to Fig.1, theiunits of the press line, and bothpull units, areall driven in unison by a common drive .shaft 82driven by a-motor 84through suitable belts 86'. The gearing between theshaft 82- and thegravure cylinder shafts is shown at 90, 92, 9 5, 96, 98, respectively.This ordinarily includes running register mechanism of thedifferentialgear typ'e, so that additional motion may-be'fed in bymeansof remotely controlled reversible acorrection motors, indicated at Mill,102,- 1d4, 106 and108; Running register Qtl'and correction motor 1%onthe first --unit 7tl are not essential, but maybe usedfor'convenienceand uniformity. The differential gear-running registers need not bedescribed in detail, for they are well known inthe art, andreferencealsomaybe made to U.S. Patent No. 2,163,035 issued'to' WilliamFJGrupe on June 20, 1939, and entitled Apparatus for Ellecting Registerof Multiple Operations.

To automatically control the registration correction motors, the web maybescanned by suitable scanners housing photoelectric cells or eyes,indicated in Fig. 2 at 110, 112, 114 and 116. These form part of aregistration control apparatus which may be of the type disclosed in US.Patent2,348,862 granted to Morris Sorkin on May 16, 1944 and entitledRegistration Control Apparatus. In that apparatus, the position of amark on the web is compared or related to the position of a mark on theprint cylinder shaft, and for this purpose, each print cylinder shaft isprovided with a socalled phase detector unit. These are indicated inFig. l at 122, 124, 126 and 128. Such units (scanner and phase detector)are not needed 'for'the first press unit 70, because the problem is tokeep the subsequent units inregistration with the first unit.

' In lieu of comparing the'position of a mark put: down on the web bythe first'unit, with the position of a mark on the second cylinder, itmay lac-compared with; a sec- 0nd mark put down on the web by the secondcylinder (which, of course, is an indication of the position of thesecond cylinder). Such a system is disclosed in US. Patent 2,151,570granted March 21, 1939 to D. R. Shoults 'et al. and entitled ControlSystem. For pur poses of the present invention; there is some differencebetween a system using scanners to compare two marks on the web, and asystem: comparing a single mark on the web with a phase detector. Eithersystem will control a correction motor to add motion to the drive :of aunit, and thus speedsitqor. .slows.it:.sligl1tly. in. order 1 to hold itin register.

structurally, there would be a. difference in the addition of anotherscanner following the last printing unit 78, this beingindicated..'at-118.in;Fig. 2. This added scanner 118 would replace thephase detector shown at 128 in Fig. 1. In passing, it maybe mentionedthat even" with. phase: detectors, the; webfscanners. may be located:(though .less, desirably), followingtheircrespec'- tive phaseizdetector,instead: of preceding thesame, in which case the scanners 112 through118.would-;be used withthe phase;detectorsz122=128z The :disadv'antageisthat; the; comparison for .registration and the resultingcorrectiontare' madelater, after an additional length: of.

webcorresponding toLthat .usedin one;printing.unit.;. In any event, thephase'detector system ismoreconvenient here,xbecause;aphase:detectoniszneeded. on at leastthe first unitfor layoff lcontrol...

Referring to Fig. .2,,.feed.unit 60 .is followedby. a dancer roll .130;-This is gievenvia.weightizcorresponding to double the desiredwebtension, oriit may be'rnadeof excessive weightiand thenrcounterbalanced.by. springs. or a weight arm', (no shown. The .dancer roll: 13%. isanounted for vertical movement, and may 'be.:provide'dwith limitswitches, notrsh'ownn Theinfinitely variable .drive' 64 is driven byshaft 32,.but-has a =remotely:controlled. reversible adjusting'rnotor.132,1 an'd the limit switches at dancer-roll 130 are connectedtomotor132. The feed velocity'is increased when" the danceriro'll- 130 rises,and is decreased. when-itfalls; in orden to keep the dancer. rollsuspended at 'an intermediateI.-point; where: its weight determinesthetension of :the W61); Theielement 132lmay behydraulic,in whichcase-its valves.are'electrically controlled, with the same end result.

As se ler-described, theapparatusishown'in Figs. 1 and 2 may beconventional. lthas: long been the practice v.and understanding of theindustry that the pressure exerted on and by impression cylinders shouldbe maintained constant. Contrary to'this prior practice, I have foundthat the maintenance of registration is greatly aided by varying thepressure applied onthe' web J by the impression cylinder in suchdirectionias: to .maintain con stant layoff of'the printedmatter ontheweb...

Referring to Fig. 3, a web'scanneris located between the printing pressunit 70, and the succeeding press unit 72. i The printed matterrputontheweb by cylinder 12*includes a marker or target, and this is repeated anumber of times along the web until the Web scanner 11% is reached. Theposition ortiming. of the: target is related to the position or timingof thecylinder 12, .by use of a so-called phase detector rotating Withcylinder 12. This is schematically shown-M in Fig.1, and in Fig. 3 isschematicallyrepresentedby a targeti tS on the cylinder cooperatingwith'a photoelectric eye- 4-4. The web scanner 110' is connectedt toapropriatecircuitry housed at 46, and the eye44=is also connected to thecircuitry at46. The arrangement may be exactly like that used forregistraiton cont-rol, as=disclosed:in the aforesaid SorkinPatent"Nor-2,348;862. The output of the circuitry at id may be usedto-"control-a remote reversible correctionmotor 48. This-inturmisused tovary the'ad justment of 'a pressure-regulator-Si), and -thus to vary thepressure exerted by the impression cylinder It will be understoodthatin' practice the hydraulic cylind l' 40-may be made double actinginstead ofsingle I acting as shown, with appropriate values to affordlifting of the impression cylinder under manual control when desired. Insome systems, the impression cylinder and its associated bearings etc.may be heavier than the desired pressure on the web, and in such case,the hydraulic cylinder 40 may be double acting in order to lessen theeffective weight of the impression cylinder, in-' stead of adding to it.Other ways to vary the pressure of cylinder 14 may be used, such ascompression springs in lieu of the hydraulic cylinders, with areversible correction motor, reduction gearing, and screws to raise orlower the stationary ends of the compression springs, and thereby varythe pressure exerted thereby.

Whatever mechanism is employed for the purpose is preferably duplicatedin each of the printing units. Thus, the impression cylinder 138 is'controlled by hydraulic cylinder 140 and pressure regulator 150, thelatter being adjusted by a correction motor 148 which in turn'iscontrolled by a web scanner 112, and a phase detector 122 operating'jointly through circuitry housed at 146. Similarly in press unit 74,the impression cylinder is controlled by web scanner 114 and phasedetector 124 connected to circuitry housed at 156 and controlling aremote correction motor 158. Similar remark applies to press units 76and 78 not shown in Fig. 3, but shown in Figs. 1 and 2.

Two separate scanners may be used between the first and second presses,one scanner for use with the phase detector 120 for layoff control, andone for use with the phase detector 122 for registration. correction.However, inasmuch as a single scanner may be wired to both circuits orcontrol panels, I here show one scanner at 110, serving both purposes.

Referring to Fig. 3, the first web scanner 110 is connected not only tothe circuitry housed at 46 to maintain uniform layoff, but also toconventional circuitry housed at 172 which controls a remote reversiblecorrection motor 102. This is the motor also shown in Fig. 1 associatedwith the running register differential gearing at 92 for feedingpositive or negative motion to the printing cylinder of press 72. Forthis purpose, the web scanner 110 makes its comparison with the phasedetector 122 on the next press 72. The phase detector may be of moreelaborate construction, such as that shown in Sorkin Patent 2,348,862previously referred to.

In similar fashion, the web scanner 112 cooperates with a precedingphase detector 122 and the circuitry 146 to control correction motor 148for uniform layoff, and the web scanner 112 cooperates with thesucceeding phase detector 124 and circuitry housed at 174 to control acorrection motor 104 which takes care of registration. Morespecifically, the motor 104 'corersponds to that shown in Fig. 1 on therunning register 94 for the press 74. Similar remark would apply to theremaining web scanners and phase detectors, nearly all of which serve adual function both for uniform layoif' and for registration. a

It is believed that the construction and operation of my improvedapparatus, as well as the advantages thereof, will be apparent from theforegoing detailed description. The usual running register mechanism maybe retained, and is preferably automatically controlled bythe usualelectric eye scanners. These may be of the double marker type (ShoultsPatent 2,151,571) or of the single marker and phase detector type(Sorkin 2,348,862). However, even when the double marker type isused,.one phase detector is employed, this being mounted on the firstpress unit, and serving for purposes of uniform layoff in the couldserve in lieu of a target on the cylinder, for pur poses of comparison.v

In general, a register correction afforded by the running registersrepresents a temporary change in speed at any one unit, to effect achange inposition at that unit, in order to achieve registration. Theamount of correctidn thus required is minimized by' maintair'u'nguniform layoffs at all of the press units, and in accordance with myinvention, this is done by appropriately varying the pressure exerted onthe web by the impression cylinders in proper direction to maintain thedesired uniform layoff.

It will be understood that while I have shown and described my improvedapparatus in a preferred form, changes may be made in the structureshown, without departing from the scope of the invention, as sought tobe defined in the following claims. In the claims, the terms marker ortarget are intended to include a selected part of the desired printedmatter, as well as a marker used solely as a target. The reference tothe web being comparatively thick means merely that the web is thickenough to result in a diiferencebetween the pitch length and the lengthsof the inner and outer faces, which difference is sufiicient to makepossible a layoff correction by pressure control as here taught.

I claim:

1. In the operation of a multicolor printing press working on acontinuous comparatively thick web, with each unit of said press havinga printing cylinder made of conventional non-yieldable material, and animpression cylinder made of conventional yieldable material, saidcylinders exerting an operating pressure on the web, the method ofhelping maintain uniform layoff and registration of the colors, whichincludes putting 'a marker on the web in .a first printing unit,scanning the marker between said first and a second printing unit tomeasure the position of the marker after a number of repeats of themarker in order to detect a change in layoff, and varying the pressureexerted in said first printing unit on the web between the printingcylinder and the impression cylinder in that direction'which helpseliminate a departure from the desired uniform layoff While maintaininga minimum pressure sufficient to pre vent slippage between the printingcylinder and the web.

2. In the operation of a multicolor printing press working on acontinuous comparatively thick web, with each unit of said press havinga printing cylinder made of conventional non-yieldable material," and animpression cylinder made of conventional yieldable material, saidcylinders exerting an operating pressure on the web, the method ofhelping maintain uniform layoff and registration of the colors, whichincludes putting a marker on the web in each printing unit, scanning themarker of each unit between that unit and the succeeding unit to measurethe position of the marker after a number of repeats of the marker inorder to detect a change in layoif in each said preceding unit, andvarying the pressure exerted on the web between the printing cylinderand the impression cylinder of each said preceding unit in thatdirection which helps eliminate a departure from the desired uniformlayoff in the said preceding unit while maintaining a minimum pressuresufficient to prevent slippage between the printing cylinder and theweb.

3. A printing press for working on a continuous comparatively thick web,said press having a printing cylinder made of conventional non-yieldablematerial, an imimpression cylinder, said operating pressure beingvariable but sufficient to prevent slippage between the printingcylinder and the web, detector means to detect a "first press, wherethere is nopreceding marker which departure from uniform layoff of theprinted matter printed on the web by the printing cylinder, and meansresponsive to said detector means for varying the pressure exerted onthe web by the aforesaid pressure exerting means in that direction whichtends to restore unieach having a printing cylinder made-of conventionalnon-yieldable material, an impression cylinder made of conventionalv.yieldable material, an operating pressure exerting means toexertipressurc on the web-between the printing cylinder and theimpression cylinder, said operatingtpressure being variable butsufiicient-to prevent slippage between the printing cylinder and theWeb, detector means to detect a departure from'uniform layoff of theprinted matter printed on the web by the printing cylinder, and meansresponsive to said detector means for varying the pressure exertedon'the web by the aforesaid pressure exertin means inthatdirection'which tends to restore uniform layoif in order to helpmaintain registration of the-colors.

5. -A multiple printing press working on a continuous comparativelythick web, each unit of said press having duced in said first unit, andmeans responsive to said web scanning means for varying the pressureexerted on the web in said first unit in that direction which helpsrestore the desired uniform layoff in the said first unit.

6. A multiple printing press working on a continuous comparatively thickweb, each unit of said press having a printing cylinder made ofconventional non-yieldable material, an impression cylinder made ofconventional yieldable material, means to exert an operating pressure onthe web between each printing cylinder and its cooperating impressioncylinder, web scanning means between a first unit and its succeedingunit arranged to detect any change in layoff of "the printed matterproduced in said first unit, means responsive to said web scanning meansfor varying the pressure exerted on the web in said first unit in thatdirection which helps restore the desired uniform layoff in the saidfirst unit, a common drive shaft for said units, running register meansbetween said drive shaft and the printing cylinder of the second unit,and means responsive to the aforesaid scanning means to supply positiveand negative motion at said running register in that direction whichhelps restore registration of the matter printed by the different unitsof the press.

7. A multiple printing press working on a continuous comparatively thickweb, each unit of said press having a printing cylinder made ofconventional non-yieldable material, an impression cylinder made ofconventional yieldable material, means to exert an operating pressure onthe web between each printing cylinder and its cooperating impressioncylinder, said operating pressure being variable but suflicient toprevent slip-page between the printing cylinder and the web, webscanning means between each unit and its succeeding unit arranged todetect any change in laycif of the printed matter produced in each saidpreceding unit, and means responsive to each web scanning means forvarying the pressure exerted on the web in each said preceding'unit inthat direction which helps restore the desired uni-form layoff in thesaid preceding unit. a

'8. .A multiple printing press working on acontinuous comparativelythick web, each unit of said press having I yieldaole material, means toexert an operating pressure on the web between each printing cylinderand itemoperating impression cylinder, 1 web scanning means between eachunit and its succeeding unit arranged to detectany change in layoffof-the printed matter produced in each said-preceding unit, and meansresponsive to each web'scanning means for varying the pressure exertedon the web in each said preceding unit in that direction whichhelpsrestore the desired uniform layoff in the .said precedingunit, a commondrive shaft for said units, running register 'means between said driveshaft and the printing cylinder of the second and succeeding units, andmeans responsive to said web scanning means to supply positive ornegative motion at said running registers as needed to help-restoreregistration in the event ofdeparturefrom registration of the matterprinted by thedilferent units of the press.

9. A multiple printing press working on continuous comparatively thickweb, .each unit of said press having a printing cylinder made ofconventional non-yieldable material, an impression cylindermade-ef'conventional yieldable material, means to exert an operatingpressure on the Web between each printing cylinder and its cooperatingimpression cylinder, said opearting pressure being variable butsufiicient to prevent slippage between the printing cylinder and theweb, web scanning means between a first unit and its succeeding unitarranged to detect any .change :in layoff of the printed matter producedin said first unit, means responsive to said'weo scanning means forvarying the pressure exerted on the web in said first aunitin thatdirection which helps restore the desired uniform lay-off in the saidfirst unit, a common drive shaft EfOl said units, running register meansbetween said drive shaft and the-printing cylinder of the secondunit,and means responsive to the aforesaid web' scanningmeansto supplypositive and negative motion at said running register in thatdirectionwhich helps rest-ore registration of the matter'printed by thedifferent units of the press.

10. A multiple p-rinting'press working on a continuouscomparativelythick web, each unit of said press having a printingcylinder made of conventional non-yieldable material, an impressioncylinder made of conventional yieldable material, means to exert anoperating pressure on the web between each printing cylinder and itscooperating impression cylinder, said operating pressure being variablebut sufficient to prevent slippage between the printing cylinder and theweb, web scanning means between each unit and its succeeding unitarranged to detect any change in layoff of the printed matter producedin each said preceding unit, and means responsive to each web scanningmeans for varying the pressure exerted on the web in each said precedingunit in that direction which helps restore the desired uniform layoff inthe said preceding unit, a common drive shaft for said units, runningregister means between said drive shaft and the printing cylinder of thesecond and succeeding units, and means responsive to the aforesaid webscanning means to supply positive or negative motion at said runningregisters as needed to help restore registration in the event ofdeparture from registration of the matter printed by the different unitsof thepress.

References Cited in the file of this patent UNITED STATES PATENTS1,460,206 a 1923 2,036,835 1936 2,500,230 1950 2,583,580 Ludwig Jan. 29,1952 2,651,256

Huck Sept. 8, 1953

